1. Technical Field
The present invention relates to bearing retainer units provided with a bearing bushing that anchors a bearing mechanism made up of upper- and lower-end bearings, and to electric motors furnished with such bearing retainer units.
2. Description of the Related Art
Motors furnished with a metal bearing bushing for anchoring upper-/lower-end bearing-equipped bearing mechanisms are known. For example, impeller-encompassing fan housings are formed, from synthetic resin, integrally with a motor support part for supporting the motor, and a cylindrical metal bearing liner is insert-molded into the motor support part. An upper-end bearing and a lower-end bearing, for rotatably supporting the rotor component of the motor, are fixed to the inner circumferential surface of the bearing liner, while the stator component of the motor is fixed to the outer circumferential surface of the bearing liner.
Along the inner periphery of the bearing liner, a projecting part that supports the upper- and lower-end bearings is by a pressing operation formed extending radially from the bearing-liner inner periphery. A consequence of this method is that precision-forming the projecting part is difficult. Furthermore, the excessive stress that acts on the bearing liner in press-forming the projecting part can compromise the roundness of the cylindrical bearing liner, leading to the bearings or stator being installed tilted.
Lack of precision in the bearing liner components leads to canted rotation of the rotor, such that noise issues from the bearings, and gives rise to the problem of excess load being placed on the bearings, decreasing their lifespan.
Thus, due to the bearing liner and the projecting part being produced by press-forming in a pressing operation, improving the precision of the bearing liner components, and the precision of the motor rotation, has been elusive.